Believe in them

Don't ignore your student, if you see he is not interested in your subject, or he doesn't understand anything. Just try to believe in everyone, and don't leave any of your students behind. Ask each of them to explain what exactly they don't like or understand, explain this once again, make sure they've got it this time. It is very important for a student to feel the support of his teacher and know, that he will always help when it is needed.